The goal of this research project is to identify therapeutic targets for the treatment of hydrocephalus. Hydrocephalus (HC) is a major clinical disorder affecting ~0.1% of the population in the United States and costing this country more than a billion dollars annually. At this time, there are no drug based therapeutic approaches for treating HC. All cases of HC are treated using shunts to decrease ventricular pressure. More than 30% of all new shunts fail in the first year and more than two thirds of new shunts fail during a ten year period. Further, 2.7 % of HC patients receiving shunts die from complications associated with the surgical procedure. In spite of these statistics, the general approach to treating HC has not changed significantly in over fifty years. The lack of progress in the treatment of HC stems, in large part, from the fact that the causes of HC are multifactorial involving both genetic mutations and environmental insults. Further, the cellular basis and molecular pathways primarily responsible for the development of HC remain largely unknown. A number of animal models of HC have been developed;however, most of these have multiple pathologies in addition to HC. As a result, it has been difficult to sort out cellular mechanisms important in the development of HC. Studies with human fetuses, which include HC arising from different mutations, suggest that ependymal denudation followed by closure of the aqueduct of Sylvius occurs in most cases of congenital HC. These and other studies support the hypothesis that an early event occurring in most forms of HC is the loss or dysfunction of ventricular ependymal cells and consequent closure of the aqueduct of Sylvius, the primary exit pathway for brain CSF. We propose two sets of experiments. First, we propose to use a newly developed mouse model of HC to identify genomic and proteomic changes that occur in ependymal cells prior to the development of overt HC. This new model of HC, referred to as Ro1HC, is based on the over expression of a Gi coupled GPCR in cells expressing glial fibrillary acidic protein (GFAP). We made this model using a tetracycline inducible regulatory system that enables us to control the timing and level of gene expression in cells expressing GFAP. Importantly, pathology observed in these mice closely resembles that observed in human HC, including the early ependymal denudation and subsequent closure of the aqueduct of Sylvius. Second, we propose to identify in vitro correlates of HC that can be used to screen for small molecules capable of interfering with the development or maintenance of HC. PUBLIC HEALTH RELEVANCE: The goal of this grant proposal is to identify the key mechanisms that lead to hydrocephalus as well as develop an in vitro correlate of hydrocephalus that can be used to screen for small molecules capable of treating this disease. Hydrocephalus is a major clinical disorder affecting ~0.1% of the population in the United States and costing this country more than a billion dollars annually. The only current treatment of hydrocephalus is based on surgically-implanting shunts designed to relieve intraventricular pressure. More than 30% of all new shunts fail in the first year and more than two thirds of shunts fail within ten years;2.7% of hydrocephalic patients receiving shunts die from complications associated with the surgical procedure.